The present invention relates to plugging compositions for blast furnace tap holes which are muddy in consistancy and are characterized by containing a phenolic resin chemically modified by reaction with lignin as a binder.
Tar has been previously employed as a binder for such plugging compositions. However, a plug formed from such compositions hardens slowly and has poor bonding strength at high temperature conditions. In addition, compositions containing tar generate a considerable amount of smoke causing serious air contamination problems and occupational health problems.
The substitution of conventional phenolic resins for tar as a binder for plugging compositions has been suggested. The use of such phenolic resins in these compositions is often characterized by a high bonding strength in the low temperature range (i.e., 200.degree. C-400.degree. C) which may cause the material to solidify prematurely in the applicator and make tapping difficult once the plug has been formed. A further disadvantage of conventional phenolic resin binders is their high cost.
The use of phenolic resins chemically modified with lignin and/or molasses as binders for refractory compositions was disclosed in copending application Ser. No. 639,679, wherein it was found that such compositions have superior refractory properties as compared to conventional tar, pitches, ordinary phenolic and furan resins.